Linear Joint Identification for Frictional Rotor Shaft-to-Hub Connections Using Frequency-Based Substructuring

Hubs, bearings, and other rotor components can be connected to rotor shafts with connections that are mechanically locked, friction-based, bonded, or a combination of these. In order to create accurate, predictive models of rotor systems, the stiffness and damping or the dynamics of these connections must be known in advance. Substructuring techniques provide methods for the identification of linear joints. Linear joint identification techniques have been presented for some engineering connections like bolted joints or rubbers. This contribution presents a workflow to identify shaft-to-hub connection dynamics on the example of a friction-based connection via cone clamping elements. A system with two parts connected by the clamping element is designed, and frequency response functions (FRFs) are measured on the assembly and on the individual parts. Using a virtual point transformation, the dynamics are projected in a collocated connection point in 6 degrees of freedom, and quasistatic and dynamic substructuring is used to isolate the connection element. Stiffness is identified from the isolated joint. The methodology is validated by comparing resynthesized FRFs on the test structure, giving good agreement for some directions.